The present invention is directed to marking materials containing retroreflective fillers. In one embodiment, the marking materials are capable of generating images that are not easily visible under ordinary viewing conditions but which are capable of being rendered readable either by the human eye or by a machine. In another embodiment, the marking materials are capable of generating images that are visible and which can be distinguished from other visible marking materials that don't contain the retroreflective filler, either by the human eye under special viewing conditions or by a machine. One specific embodiment of the present invention is directed to a process for generating images on paper which comprises applying in imagewise fashion to the paper a marking material containing a retroreflective filler material. Another embodiment of the present invention is directed to a toner composition for the development of electrostatic latent images which comprises a thermoplastic resin and a retroreflective filler material. Yet another embodiment of the present invention is directed to a process for generating images which comprises generating an electrostatic latent image on an imaging member in an imaging apparatus; developing the latent image with a toner comprising a thermoplastic resin and a retroreflecting filler material; optionally transferring the developed image to a substrate; and optionally permanently affixing the transferred image to the substrate. Still another embodiment of the present invention is directed to an imaging process which comprises (1) charging an imaging member in an imaging apparatus; (2) creating on the member a latent image comprising areas of high, intermediate, and low potential; (3) developing the low areas of potential with a first developer comprising a first toner comprising a thermoplastic resin, an optional colorant, and an optional retroreflecting filler; (4) subsequently developing the high areas of potential with a second developer comprising a second toner comprising a thermoplastic resin, an optional colorant, and an optional retroreflecting filler; and (5) transferring the developed images to a substrate, wherein a retroreflecting filler is necessarily present in either the first toner or the second toner, and wherein a colorant is necessarily present in a toner containing no retroreflecting filler. Another embodiment of the present invention is directed to a process which comprises incorporating into an ink jet printer an ink composition comprising a vehicle, an optional colorant, and a retroreflecting filler, and causing droplets of the ink composition to be ejected in an imagewise pattern onto a substrate. In a preferred embodiment, the ink comprises an aqueous liquid vehicle and the ink is incorporated into a thermal ink jet printer. Yet another embodiment of the present invention is directed to a process for generating images which comprises generating an electrostatic latent image on an imaging member in an imaging apparatus; developing the latent image with a toner comprising a thermoplastic resin and a colorant; transferring the developed image to a substrate; optionally permanently affixing the transferred image to the substrate; and causing droplets of an ink composition comprising an aqueous liquid vehicle, an optional colorant, and a retroreflecting filler to be ejected in an imagewise pattern onto the substrate. Still another embodiment of the present invention is directed to an ink composition which comprises an aqueous liquid vehicle and a retroreflective filler material, said ink composition having a viscosity of no more than about 5 centipoise. Another embodiment of the present invention is directed to a liquid developer for the development of electrostatic latent images which comprises a nonaqueous liquid vehicle, an optional charge control agent, and retroreflective filler particles, said developer having a resistivity of at least about 10.sup.8 and a viscosity of no more than 500 centipoise at the temperature at which development occurs. Yet another embodiment of the present invention is directed to an imaging process which comprises generating an electrostatic latent image on an imaging member and contacting the latent image with a liquid developer comprising a nonaqueous liquid vehicle, a charge control agent, and toner particles comprising retroreflective filler particles, thereby causing the toner particles to migrate through the liquid and develop the latent image. Still another embodiment of the present invention is directed to an imaging process which comprises generating an electrostatic latent image on an imaging member, applying to an applicator a liquid developer comprising a nonaqueous liquid vehicle and retroreflective filler particles, and bringing the applicator into sufficient proximity with the latent image to cause the image to attract the developer onto the imaging member, thereby developing the image. Another embodiment of the present invention is directed to an imaging process which comprises applying a liquid to a substrate in imagewise fashion, followed by applying retroreflective filler particles to the liquid image. Yet another embodiment of the present invention is directed to a process for controlling a reproduction system, comprising the steps of: (1) scanning an image to detect retroreflective filler material in at least one marking material forming the image; and (2) issuing instructions to the reproduction system, wherein the instructions cause the reproduction system to take an action selected from the group consisting of: (a) prohibiting reproduction of those portions of the image formed by marking material containing retroreflective filler material, and reproducing of all other portions of the image; (b) prohibiting reproduction of any part of the image upon detection of retroreflective filler material; (c) reproducing only those portions of the image formed by marking material containing retroreflective filler material; (d) reproducing portions of the image formed by marking material containing retroreflective filler material in a different manner from that in which the system reproduces portions of the image formed by marking material not containing retroreflective filler material; and (e) identifying a source of the image on the basis of detection of retroreflective filler material. Still another embodiment of the present invention is directed to a process for determining the relative position of a movable component in an imaging apparatus which comprises (a) providing on the movable component at least one mark with a marking material containing a retroreflective filler material; (b) positioning an illumination source so that illumination from the illumination source strikes the mark on the movable component; (c) positioning an illumination detector so that it can detect illumination reflected from the retroreflective filler material on the movable component; and (d) calculating the relative position of the movable component using information provided from the illumination detector.
U.S. Pat. No. 4,948,686 (Koch et al.), the disclosure of which is totally incorporated herein by reference, discloses a process for forming two-color images which comprises charging an imaging member, creating on the member a latent image comprising areas of high, medium, and low potential, developing the low areas of potential with a developer comprising a specific colored toner and a specific carrier, subsequently developing the high areas of potential with a developer comprising a specific black toner and a specific carrier, transferring the developed two-color image to a substrate, and permanently affixing the image to the substrate.
U.S. Pat. No. 4,135,664 (Resh), the disclosure of which is totally incorporated herein by reference, discloses a lateral register control system utilizing a reference lateral and circumferential mark pair preprinted on the web which is compared with a corresponding mark pair mounted on a drum coupled to the shaft of the print cylinder whose reference is to be controlled. The clock source is an encoder connected to the same print stand as laid down the reference marks on the web. The contents of the cylinder position counters are always slightly greater than the contents of the scanner difference counters and are counted up slightly before the scanner difference counters. Upon sensing a first reference mark on the web, the scanner difference counters are permitted to count. Upon the second reference mark being sensed, the fine adjust counters are permitted to start counting. Upon the contents of the fine adjust counters equaling the value of operator setable fine adjust switches, an error pulse train is generated having an associated sign. The error pulse train is accumulated in a repeat counter and is terminated when the contents of the scanner difference counters equal the contents of the cylinder position counters. The error magnitude may be averaged over several cycles or output directly to a digital analog converter which produces an analog error magnitude. This magnitude serves as the input to the motor control circuitry. The motor control circuitry is operable to drive the print cylinder lateral position motor at a rate proportional to the analog error signal and in the direction indicated by the sign of the error signal.
U.S. Pat. No. 5,175,570 (Haneda et al.), the disclosure of which is totally incorporated herein by reference, discloses a color image forming apparatus in which at least one registration mark is formed on a movable image retainer, and exposed by an exposing device. A position of the registration mark is detected by a detecting device and a signal is generated based on the detected position of the registration mark. An exposing position of the exposing device is corrected by a correcting device in accordance with the signal to form a latent image on the image retainer.
U.S. Pat. No. 5,175,564 (Jamzadeh), the disclosure of which is totally incorporated herein by reference, discloses a color printer which includes a recording element which is advanced along a path to receive color-separation images of a desired multicolor image to be printed. Color-separation image recording is effected by a laser scanner which operates asynchronously with respect to the movement of the recording element and functions to periodically scan an intensity-modulated beam of radiation across the moving recording element to record a multitude of equally spaced image lines that collectively define a two-dimensional latent image. In response to a print enable signal, the laser scanner begins scanning the first line of a color-separation image at any time within a line-time interval required to scan each image line. According to a preferred embodiment of the invention, the print enable signal is provided a predetermined fraction of the line-time interval earlier for the second and subsequent color-separation images of a desired multicolor image than it is for the first color-separation image. In this manner the color-separated images are better registered with respect to a nominal position on the recording element.
U.S. Pat. Re. 32,967 (St. John et al.), the disclosure of which is totally incorporated herein by reference, discloses a web tracking system for a continuous web of material which is transported from a supply to a takeup means along a predetermined path via one or more processing stations and comprises aligned tracking indicia along at least one edge of the web. Means are provided to observe the tracking indicia as the web is transported along the system path and produce information either indicative of dimensional changes in the length and width of the web due to web shrinkage or expansion or indicative of a particular point along the length of the web useful at one or more of the processing stations in the system.
U.S. Pat. No. 4,963,899 (Resch), the disclosure of which is totally incorporated herein by reference, discloses an image frame registration apparatus and method which have particular utility in a printing or reproduction apparatus that processes multiple image frames on a transported photosensitive member. Registration indicia for registering an image frame are written on the photosensitive member in an interframe or frame margin area. The indicia are composed of discharged line patterns that are readable by a sensor array according to the charge variation or, after toning, the pattern of toned lines therein. The sensor array provides in-track and cross-track signal information to a control unit for synchronizing the electrostatographic processing of the registered image frames. In particular, servo-controlled drive means in the exposure and transfer stations are controlled with precision to provide, after the development and transfer of several registered component images to one or more receivers, an accurate multicolor reproduction.
U.S. Pat. No. 4,912,491 (Hoshino et al.), the disclosure of which is totally incorporated herein by reference, discloses an image forming apparatus for forming superimposed images which includes a plurality of image forming devices each for forming a different image and a registration mark, corresponding to the position of the associated image, on an image transferring medium. The registration mark is formed on a transparent part of the medium and is illuminated from below. A detector above the medium detects the position of the shadow of the registration mark for each image and the result of detection is used to adjust the position of at least one image forming device to produce proper registration between the images formed by the respective image forming devices.
U.S. Pat. No. 5,208,796 (Wong et al.), the disclosure of which is totally incorporated herein by reference, discloses a method and apparatus for transverse registration of image exposures on photoreceptive belts subject to lateral deviation from linear travel in which targets, corresponding in location to the image areas to be exposed, are used for the detection of lateral belt displacement and to control the transverse location of exposure scan. The targets are of a pattern defining a reference line and a line inclined with respect to the direction of belt travel so that the duration of time between passage of the target lines with respect to a spatially fixed sensing axis will vary with lateral displacement of the belt. The targets may assume a variety of specific patterns and the invention is applicable to single and multi-pass image exposure systems as well as to both modulated laser and light emitting diode types of exposure devices.
U.S. Pat. No. 5,204,620 (Costanza et al.), the disclosure of which is totally incorporated herein by reference, discloses a method for measuring accurately the actual position and velocity of a photoreceptor belt by sensing the passing of illuminated holes in the belt, as the belt moves in a process direction. A segmented sensor array is positioned so as to view the passing of the illuminated holes. A Gaussian light intensity distribution is sensed by a group of sensor pixels which sense the light during a sampling interval. The array produces an output which is operated upon by a centroid processor to determine the center of moment for each sampled intensity distribution. A prediction is then made for projected position of the belt which is very accurate since the centroid calculation is not affected by noise produced by stray light or poorly defined image edges.
U.S. Pat. No. 5,160,946 (Hwang), the disclosure of which is totally incorporated herein by reference, discloses an electrophotographic printing machine which utilizes an improved image registration system that forms and senses image registration indicia to control a subsequent transfer of a visible image. A first transfer station transfers registration indicia, previously formed on a first photoconductive member and transferred therefrom, onto a receiving member. A sensor monitors the registration indicia on the receiving member and generates a control signal indicative thereof. A second transfer station, responsive to the control signal, transfers a visible image, previously formed on a second photoconductive member and transferred therefrom, to the receiving member.
Further information with respect to registration marks on imaging members is disclosed in, for example, copending application U.S. Ser. No. 07/807,927, filed Dec. 16, 1991, now U.S. Pat. No. 5,302,973, entitled "Method and Apparatus for Image Registration In a Single Pass ROS," with the named inventors Daniel W. Costanza and William J. Nowak, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/946,703, filed Sep. 18, 1992, now U.S. Pat. No. 5,260,725, entitled "Method and Apparatus for Registration of Sequential Images in a Single Pass, Color Xerographic Printer," with the named inventor Thomas J. Hammond, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/931,802, filed Aug. 18, 1992, now U.S. Pat. No. 5,278,625, entitled "Method and Apparatus for Lateral Registration of Sequential Images in a Single Pass Multi-LED Print Bar Printer," with the named inventors George A. Charnitski and Jacob N. Kluger, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/859,746, filed Mar. 30, 1992, entitled "Apparatus for Transverse Image Registration of a Photoreceptor Belt," with the named inventors Ssujan Hou and Lam F. Wong, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/991,228, filed Dec. 16, 1992, now U.S. Pat. No. 5,321,434, entitled "Digital Color Printer With Improved Lateral Registration," with the named inventors Andrew M. Strauch, Fred F. Hubble III, and Kenneth R. Ossman, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/970,889, filed Nov. 3, 1992, now U.S. Pat. No. 5,278,587, entitled "Method and Apparatus for Image Registration," with the named inventors Andrew M. Strauch, Daniel W. Costanza, Kenneth R. Ossman, and Fred F. Hubble III, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 08/055,335, filed May 3, 1992, now U.S. Pat. No. 5,412,409, entitled "Image Registration For a Raster Output Scanner (ROS) Color Printer," with the named inventor Daniel W. Costanza, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/995,650, filed Dec. 18, 1992, entitled "Transverse Image Registration For a Digital Color Printer," with the named inventor Edward A. Powers, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/807,931, filed Dec. 16, 1991, now U.S. Pat. No. 5,300,961, entitled "Method and Apparatus for Aligning Multiple Image Print Bars in a Single Pass System," with the named inventors Stephen C. Corona and George A. Charnitski, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/821,526, filed Jan. 16, 1992, now U.S. Pat. No. 5,442,388, entitled "Method and Means for Correcting Lateral Registration Errors," with the named inventor Richard A. Schieck, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/992,685, filed Dec. 18, 1992, now U.S. Pat. No. 5,248,027, entitled "Method and Apparatus for Belt Steering Control," with the named inventors Jacob N. Kluger, Ssujan Hou, Lam F. Wong, and Stephen C. Arnone, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 07/862,150, filed Apr. 2, 1992, now U.S. Pat. No. 5,272,493, entitled "Method and Apparatus for Registration of Sequential Images in a Single Pass, Multi-LED Printbar Printer," with the named inventors Fred F. Hubble III, Thomas J. Hammond, and James P. Martin, the disclosure of which is totally incorporated herein by reference; copending application U.S. Ser. No. 08/063,796, filed May 20, 1993, now U.S. Pat. No. 5,383,014, entitled "Photoreceptor Belt Motion Sensor Using Linear Position Sensors," with the named inventors William J. Nowak, Daniel W. Costanza, Edward A. Powers, the disclosure of which is totally incorporated herein by reference; and copending application U.S. Ser. No. 08/035,830, filed Mar. 23, 1993, now U.S. Pat. No. 5,339,150, entitled "Mark Detection Circuit for an Electrographic Printing Machine," with the named inventors Fred F. Hubble Ill, James P. Martin, and Jeffrey J. Folkins, the disclosure of which is totally incorporated herein by reference, and in U.S. Pat. No. 4,837,636, U.S. Pat. No. 4,893,135, U.S. Pat. No. 4,916,547, U.S. Pat. No. 4,804,979, U.S. Pat. No. 4,401,024, U.S. Pat. No. 4,965,597, U.S. Pat. No. 4,903,067, and U.S. Pat. No. 5,016,062, the disclosures of each of which are totally incorporated herein by reference.
U.S. Pat. No. 5,225,900 (Wright), the disclosure of which is totally incorporated herein by reference, discloses apparatuses and processes for controlling a reproduction system by scanning an image to detect at least one taggant in at least one marking material forming the image and issuing instructions to the reproduction system; the instructions cause the reproduction system to take an action selected from the group consisting of (a) prohibiting reproduction of those portions of the image formed by a marking material containing at least one predetermined detected taggant and reproducing all other portions of the image; (b) prohibiting reproduction of any part of the image upon detection of at least one predetermined taggant; (c) reproducing only those portions of the image formed by a marking material containing at least one predetermined taggant; (d) reproducing portions of the image formed by a marking material containing at least one predetermined taggant in a different manner from that in which the system reproduces portions of the image formed by a marking material not containing at least one predetermined taggant; and (e) identifying a source of the image on the basis of detection of at least one predetermined taggant.
U.S. Pat. No. 5,145,518 (Winnik et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink composition which comprises an aqueous liquid vehicle and particles of an average diameter of 100 nanometers or less which comprise micelies of block copolymers of the formula ABA, wherein A represents a hydrophilic segment and B represents a hydrophobic segment, and wherein dye molecules are covalently attached to the micelies, said dye molecules being detectable when exposed to radiation outside the visible wavelength range. Optionally, silica is precipitated within the micelies. In a specific embodiment, the dye molecules are substantially colorless. In another specific embodiment, the ink also contains a colorant detectable in the visible wavelength range.
Although known compositions and processes are suitable for their intended purposes, a need remains for marking materials capable of generating images that are not easily visible under ordinary viewing conditions but which are capable of being rendered readable either by the human eye or by a machine. In addition, a need remains for marking materials capable of generating images that are visible and which can be distinguished from other visible marking materials that do not contain the retroreflective filler, either by the human eye under special viewing conditions or by a machine. Further, there is a need for marking materials capable of generating images that are detectable with retroreflecting optics wherein the detector is substantially colinear with the illumination source and the angle of illumination is off the normal. Additionally, a need remains for processes wherein both visible images and images substantially invisible to the naked eye but capable of detection by either a machine or by the human eye under special viewing conditions are applied to a substrate by an electrophotographic process in a single development pass. There is also a need for processes wherein images of two different colored toners are both applied to a substrate by an electrophotographic process in a single development pass, with at least one of the colored toners contains a retroreflective filler material capable of detection by either a machine or by the human eye under special viewing conditions. In addition, a need exists for processes wherein a first image is applied to a substrate by an electrophotographic process and a second image is applied to the substrate by an ink jet printing process, wherein one of the images contains retroreflective filler material capable of detection by either a machine or by the human eye under special viewing conditions. Further, there is a need for processes for placing encoded information in a document in a manner not distracting or easily visible to the casual user. Additionally, there is a need for methods for placing timing marks on moving components of imaging apparatuses, such as imaging members, intermediate transfer elements, or the like to enable optical detectors to determine the relative position of a particular portion of the member with respect to the rest of the machine.